Abstract
The Weddell seal population in Erebus Bay, Antarctica, represents one of the best-studied marine mammal populations in the world, providing an ideal test for the efficacy of satellite imagery to inform about seal abundance and population trends. Using high-resolution (0.6 m) satellite imagery, we compared counts from imagery to ground counts of adult Weddell seals and determined temporal trends in Erebus Bay during November 2004–2006 and 2009, and December 2007. Seals were counted from QuickBird-2 and WorldView-1 images, and these counts were compared with ground counts at overlapping locations within Erebus Bay during the same time. Counts were compared across years and within individual haul-out locations. We counted a total of 1,000 adult Weddell seals from five images across all years (for a total of 21 satellite-to-ground count comparisons), approximately 72% of the total counted on the ground at overlapping locations. We accurately detected an increase in abundance during 2004–2009. There was a strong, positive correlation (r = 0.98, df = 3, P < 0.003) between ground counts and counts derived from the imagery. The correlation between counts at individual haul-out locations was also strong (r = 0.80, df = 19, P < 0.001). Detection rates ranged from 30 to 88%. Overall, our results showed the utility of high-resolution imagery to provide an accurate way to detect the presence and variation in abundance of Weddell seals. Our methods may be applied to other species in polar regions, such as walruses or polar bears, particularly in areas where little is known about population status.
Similar content being viewed by others
References
Ackley SF et al (2002) A top-down, multi-disciplinary study of the structure and function of the pack ice ecosystem in the eastern Ross Sea, Antarctica. Polar Rec 39:219–231
Ainley DG, Siniff DB (2009) The importance of Antarctic toothfish as prey of Weddell seals in the Ross Sea: a review. Antarc Sci 21:317–327
Arrigo KR, van Dijken GL, Ainley DG, Fahnestock MA, Markus T (2002) Ecological impact of a large Antarctic iceberg. Geophys Res Lett doi:10.1029/2001GL014160
Barber-Meyer SM, Kooyman GL, Ponganis PJ (2007) Estimating the relative abundance of emperor penguins at inaccessible colonies using satellite imagery. Polar Biol 30:1565–1570
Bengston JL, Stewart BS (1992) Diving and haul-out behavior of crabeater seals in the Weddell Sea, Antarctica, during March 1986. Polar Biol 12:635–644
Bengston JL et al. (2011) Distribution, density, and abundance of pack-ice seals in the Amundsen and Ross Seas, Antarctica. Deep Sea Res. doi:10.1016/j.dsr2.2010.10.037
Bester MN, Stewart BS (2006) The international antarctic pack ice seals (APIS) program multi-disciplinary research into the ecology and behavior of Antarctic Pack Ice Seals Summary Update. SCAR Expert Group on Seals, 25 pp
Bester MN, Ferguson JWH, Jonker FC (2002) Population densities of pack ice seals in the Lazarev Sea, Antarctica. Antarc Sci 14:123–127
Blight LK et al (2010) Fishing for data in the Ross Sea. Sci Lett 330:1316
Boyd IL, Bowen WD, Iverson SJ (2010) Marine mammal ecology and conservation: a handbook of techniques. Oxford, New York
Buckland ST, Anderson DR, Burnham KP, Laake JL, Borchers DL, Thomas L (2001) Introduction to distance sampling: estimating abundance of biological populations. Oxford University Press, Oxford
Burns JJ, Harbo SJ (1972) An aerial census of ringed seals, northern coast of Alaska. Arctic 25:279–290
Burns JM, Kooyman GL (2001) Habitat use by Weddell seals and emperor penguins foraging in the Ross Sea, Antarctica. Am Zool 41(1):90–98
Cameron MF, Siniff DB (2004) Age-specific survival, abundance, and immigration rates of a Weddell seal (Leptonychotes weddellii) population in McMurdo Sound, Antarctica. Can J Zool 82:601–615
Cameron MF, Siniff DB, Proffitt KM, Garrott RA (2007) Site fidelity of Weddell seals: the effects of sex and age. Antarc Sci 19:149–155
Constable AJ, de la Mare WK, Agnew DJ, Everson I, Miller D (2000) Managing fisheries to conserve the Antarctic marine ecosystem: practical implementation of the convention on the conservation of antarctic marine living resources (CCAMLR). ICES J Mar Sci 57:778–791
Croxall JP, Hiby L (1983) Fecundity, survival and site fidelity in Weddell seals (Leptonychotes weddellii) population in McMurdo Sound, Antarctica. Can J Zool 82:601–615
Croxall JP, Kirkwood Ed (1979) The distribution of penguins on the Antarctic Peninsula and island of the Scotia Sea. Brit Antarc Surv 10:1–186
Croxall JP, Nicol S (2004) Management of Southern Ocean fisheries: global forces and future sustainability. Antarc Sci 16:569–584
Eberhardt LL, Chapman DG, Gilbert JR (1979) A review of marine mammal census methods. Wildl Monogr 63:3–46
Environmental Systems Research Institute (2009) ArcGIS 9.3. Redlands, California
Erickson AW, Bledsoe LJ, Hanson MB (1989) Bootstrap correction for diurnal activity cycle in census data for Antarctic seals. Mar Mamm Sci 5:29–56
Flores H, Haas C, van Frankener JA, Meesters E (2008) Density of pack ice seals and penguins in the western Weddell Sea in relation to ice thickness and ocean depth. Deep Sea Res 55:1068–1074
Fossey D, Harcourt AH (1977) Feeding ecology of free-ranging mountain gorilla. In: Brock TH (ed) Primate ecology: studies of feeding behavior in lemurs, monkeys, and apes. Academic, New York, pp 449–479
Fretwell PT, Trathan PN (2009) Penguins from space: faceal stains reveal the location of emperor penguin colonies. Glob Ecol and Biogeogr 18:543–552
Garrott RA, Taylor L (1990) Dynamics of a feral horse population in Montana. J Wildl Manage 54:603–612
Gelatt TS (2001) Male reproductive success, relatedness, and the mating system of Weddell seals in McMurdo Sound, Antarctica. Dissertation, University of Minnesota
Gelatt TS, Siniff DB (1999) Line transect survey of crabeater seals in the Amundsen-Bellingshausen Seas, 1994. Wildl Soc Bull 27:330–336
Gelatt T, Davis CS, Cameron M, Siniff D, Strobeck C (2000) The old and the new: integrating population ecology and population genetics of Weddell seals. In: Davison W et al (eds) Antarctic ecosystems: models for a wider ecological understanding. Caxton, Christchurch, pp 63–70
Gilbert JR (1989) Aerial census of Pacific walrus, Odobenus rosmarus, in the Bering and Chukchi seas. Mar Mamm Sci 5:17–28
Green K, Burton HR, Wong V, McFarlane RA, Flaherty AA, Pahl BC, Haigh SA (1995) Difficulties in assessing population status of ice seals. Wildl Res 22:193–199
Hadley GL, Rotella JJ, Garrott RA (2007) Influence of maternal characteristics and oceanographic conditions on survival and recruitment probabilities of Weddell seals. Oikos 116:601–613
Hastings KK, Testa JW (1998) Maternal and birth colony effects on survival of Weddell seal offspring from McMurdo Sound, Antarctica. J Anim Ecol 67:722–740
Johnston DW, Meisenheimer P, Lavigne DM (2000) An evaluation of management objectives for Canada’s commercial harp seal hunt, 1996–1998. Cons Biol 14:729–737
Lake SE, Burton HR, Hindell MA (1997) Influence of time of day and month on Weddell seal haul-out patterns at the Vestfold Hills, Antarctica. Polar Biol 18:319–324
Lavigne DM, Innes S, Kalpakis K, Ronald K (1982) An aerial census of Western Atlantic harp seals (Pagophilus groenlandicus) using ultraviolet photography. In: Mammals in the Seas, FAO Fisheries Series (5) IV, pp 295–302
Lindsey AA (1937) The Weddell seal in the Bay of Whales, Antarctica. J Mammal 18:127–144
MacKenzie DI, Nicols JD, Royle JA, Pollock KH, Bailey LL, Hines JE (2005) Occupancy estimation and modeling: inferring patterns and dynamics of species occurrence. Elsevier, San Diego
McLaren IA (1966) Analysis of an aerial census of ringed seals. J Fish Res Board Can 23:769–773
Micol T, Jouventin P (2000) Long-term population trends in seven Antarctic sea birds at Pointe Geologie (Terre Adelie). Polar Biol 24:175–185
NMML (National Marine Mammal Laboratory) (2007) Polar ecosystems research: Harbor seal census in Southeast Alaska. Quarterly Report, Alaska Fisheries Science Center, Juneau. http://www.afsc.noaa.gov/Quarterly/jas2007/divrptsNMML4.htm. Accessed 15 Feb 2011
Ponganis PJ, Stockard TK (2007) The Antarctic toothfish: how common a prey for Weddell seals? Antarc Sci 19:441–442
Rotella JJ, Link WA, Nichols JD, Hadley GL, Garrott RA, Proffitt KM (2009) An evaluation of density-dependent and -independent influences on population growth rates in Weddell seals. Ecology 90:975–984
Siniff DB (1981) Seal population dynamics and ecology. J R Soc NZ 11:317–327
Siniff DB, Testa JR, Kuechle VB (1971) Some observations on the activity patterns of Weddell seals as recorded by telemetry. Antarct Res Ser 18:173–180
Siniff DB, DeMaster DP, Hofman RJ, Eberhardt LL (1977) An analysis of the dynamics of a Weddell seal population. Eco Monogr 47:319–335
Siniff DB, Garrott RA, Rotella JJ, Frase WR, Ainley DG (2008) Projecting the effects of environmental change on Antarctic seals. Antarc Sci 20:425–435
Smith MSR (1965) Seasonal movements of the Weddell seal in McMurdo Sound, Antarctica. J Wildl Manage 29:464–470
Southwell C (2005a) Response behavior of seals and penguins to helicopter surveys over the pack ice off East Antarctica. Antarc Sci 17:328–334
Southwell C (2005b) Optimizing the timing of visual surveys of crabeater seal abundance: haul-out behavior as a consideration. Wildl Res 32:333–338
Southwell C, de la Mare B, Borchers D, Burt L (2004) Shipboard line transect surveys of crabeater seal abundance in the pack ice off East Antarctica: evaluation of assumptions. Mar Mamm Sci 20:602–620
Stirling I (1969a) The ecology of the Weddell seal in McMurdo Sound, Antarctica. Ecology 4:573–586
Stirling I (1969b) Distribution and abundance of the Weddell seal in the western Ross Sea, Antarctica. NZ J Mar Freshwat Res 3:191–200
Stirling I (1974) Movements of Weddell seals in McMurdo Sound, Antarctica. Aust J Zool 22:39–43
Tedman RA, Bryden MM (1979) Cow-pup behaviour of the Weddell seal, Leptonychotes weddellii (Pinnipedia), in McMurdo Sound, Antarctica. Aust Wildl Res 6:19–37
Testa JW, Siniff DB (1987) Population dynamics of Weddell seals (Leptonychotes weddellii) in McMurdo Sound, Antarctica. Ecol Monogr 57:149–166
Williams BK, Nichols JD, Conroy MJ (2002) Analysis and management of animal populations. Academic, San Diego
Wilson EA (1907) Mammalia (whales and seals). In: National Antarctic expedition 1901–1904. Nat Hist Vol 2, Zoology Pt 2, Aves London
Acknowledgments
This work was funded by National Science Foundation grants OPP-0753663, OPP-0944411 and OPP-0635739. Satellite imagery data were copyright of DigitalGlobe, Inc. and provided through the Commercial Imagery Program by the National Geospatial-Intelligence Agency. We thank the United States Air Force, Raytheon Polar Services Company, and Petroleum Helicopters International for assistance with field logistics. B. Herried provided consultation for figures and S. Barber-Meyer, C. Southwell, and M. Cameron provided valuable insight into a previous draft of the manuscript.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
LaRue, M.A., Rotella, J.J., Garrott, R.A. et al. Satellite imagery can be used to detect variation in abundance of Weddell seals (Leptonychotes weddellii) in Erebus Bay, Antarctica. Polar Biol 34, 1727–1737 (2011). https://doi.org/10.1007/s00300-011-1023-0
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00300-011-1023-0